1. Field of the Invention
The present invention relates to handover from a wireless local area network to a wireless wide area network. More particularly, the present invention relates to a handover method that initiates, when channel interference becomes severe during communication with a wireless local area network, handover to a wireless wide area network and to an apparatus supporting the handover method.
2. Description of the Related Art
IEEE 802.11 refers to a set of standards for implementing Wireless Local Area Networks (WLANs). These standards were created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802), and provide the basis for Wi-Fi wireless network technologies. There are various handover schemes used in WLANs. For example, handover may be initiated by measurement of signal strength. That is, when the strength of a signal received from the current Wi-Fi network is weak, a mobile station (e.g., a mobile terminal) may measure the strength of a beacon frame signal transmitted by a neighbor access point and initiate soft handoff. As another example, handover may be performed from a WLAN to a Wireless Wide Area Network (WWAN). That is, when a mobile station leaves the coverage of the current WLAN, automatic handover to a WWAN may be performed.
The density with which access points have been installed in recent years may cause problems. For example, communication service providers competitively install their access points in a hotspot zone to attract customers. Dense access points (e.g., access points densely installed among other access points) may cause severe channel interference, which may result in data retransmission or even data loss. Thereby, communication services may be disrupted in the hotspot zone. Hence, in a hotspot zone, it is necessary to support handover from a WLAN to a WWAN. However, existing handover schemes are primarily based on signal strength measurement and may be inadequate for handling channel interference.